Dynamics of soil respiration and microbial communities: Interactive controls of temperature and substrate quality
Dynamics of soil respiration and microbial communities: Interactive controls of temperature and substrate quality
复制标题
DOI：
10.1016/j.soilbio.2018.09.010
复制
发表时间：
2018-12-01
影响因子：
9.7
通讯作者：
Kandeler, Ellen
中科院分区：
文献类型：
--
作者：
Ali, Rana Shahbaz;Poll, Christian;Kandeler, Ellen
土壤微生物群落调节土壤对气候的反馈；因此，彻底了解它们对气温升高的反应对于预测气候引起的碳(C)通量的变化至关重要。然而，目前还不清楚微生物群落将如何改变结构和功能，以响应温度的变化和有机碳的有效性，有机碳的复杂性各不相同。在这里，我们介绍了一项实验室培养研究的结果，在该研究中，土壤微生物群落暴露在不同的温度和有机碳复杂性中。土壤样本采集自德国西南部两个地区气候和土壤条件不同的两种土地利用类型。用纤维二糖(CB)、木聚糖或松柏醇(CA，木质素前体)改良的土壤在5℃、15℃或25℃下培养，我们发现温度主要控制微生物的呼吸速率。在所有底物改良剂中，温度升高促进了累积呼吸速率，但降低了微生物总生物量(总磷脂脂肪酸，PLFAs)。温度升高对真菌生物量的影响比细菌生物量更不利，真菌生物量(真菌PLFAs、麦角甾醇及其碎片)的温度响应取决于底物质量。在添加CB的情况下，真菌生物量的温度响应与未改良的对照土壤没有差异，而添加木聚糖和CA使真菌的最适温度从5℃移动到15℃。这些结果首次证明，分解复杂C底物的真菌(CA和Xylan)可能具有不同于分解不稳定C底物的真菌群落的生活策略和最适温度。革兰氏阳性菌和革兰氏阴性菌在不同温度条件下分解CB的能力有很大差异：革兰氏阳性菌在5℃时PLFA丰度最高，而革兰氏阴性菌在25℃时最丰富。通过16S rRNA基因丰度测定细菌群落组成，PLFA显示出相反的温度和底物分解趋势。利用多元统计方法，我们发现微生物的生命策略与微生物群落的关键成员之间存在着普遍的联系：寡养的阿帕蛋白细菌和酸杆菌与复杂的底物相关，共营养的放线菌与不稳定的底物相关。我们的研究提供了证据，表明碳循环对气候变暖的响应将通过土壤微生物群落结构和功能的变化来调节。
Soil microbial communities mediate soil feedbacks to climate; a thorough understanding of their response to increasing temperatures is therefore central to predict climate-induced changes in carbon (C) fluxes. However, it is unclear how microbial communities will change in structure and function in response to temperature change and to the availability of organic C which varies in complexity. Here we present results from a laboratory incubation study in which soil microbial communities were exposed to different temperatures and organic C complexity. Soil samples were collected from two land-use types differing in climatic and edaphic conditions and located in two regions in southwest Germany. Soils amended with cellobiose (CB), xylan, or coniferyl alcohol (CA, lignin precursor) were incubated at 5, 15 or 25 degrees C. We found that temperature predominantly controlled microbial respiration rates. Increasing temperature stimulated cumulative respiration rates but decreased total microbial biomass (total phospholipid fatty acids, PLFAs) in all substrate amendments. Temperature increase affected fungal biomass more adversely than bacterial biomass and the temperature response of fungal biomass (fungal PLFAs, ergosterol and ITS fragment) depended upon substrate quality. With the addition of CB, temperature response of fungal biomass did not differ from un-amended control soils, whereas addition of xylan and CA shifted the fungal temperature optima from 5 degrees C to 15 degrees C. These results provide first evidence that fungi which decompose complex C substrates (CA and xylan) may have different life strategies and temperature optima than fungal communities which decompose labile C substrate (CB). Gram-positive and gram-negative bacteria differed strongly in their capacity to decompose CB under different temperature regimes: gram-positive bacteria had highest PLFA abundance at 5 degrees C, while gram-negative bacteria were most abundant at 25 degrees C. Bacterial community composition, as measured by 16S rRNA gene abundance, and PLFAs showed opposite temperature and substrate decomposition trends. Using multivariate statistics, we found a general association of microbial life strategies and key members of the microbial community: oligotrophic Aiphaproteobacteria and Acidobacteria were associated with complex substrates and copiotrophic Actinobacteria with labile substrates. Our study provides evidence that the response of C cycling to warming will be mediated by shifts in the structure and function of soil microbial communities.